1. Field of the Invention
The present invention relates to the field of measuring the inside of an opening intended to be circular. More specifically, the invention is in the field of measuring an opening which ideally would be circular but realistically will almost always deviate from a true circle. Such openings are found on cast products such as ductile iron pipe bells. These pipe bells are preferably circular but are, due to the method of their manufacture, almost always out of round or slightly oval.
2. Prior Art Device and Methods
Prior art methods include using devices for making multiple measurements of the diameter of the openings at regular angular orientation and averaging these measurements. This prior art method yields satisfactory results but is quite time consuming since it must be determined whether the average diameter falls within the specified limits. In the case of ductile iron pipe bells, the reason for limiting the inside diameter is to assure that the spigot end of the mating pipe will enter the bell and leave only a predetermined space unoccupied. This invention of a flexible "go-no go" gauge allows immediate determination as to whether an opening falls within the limits specified.